1. Field of the Invention
This invention relates to a disk drive suspension used in an information processing apparatus provided with a disk for use as a recording medium.
2. Description of the Related Art
A hard disk drive (HDD) is used in an information processing apparatus such as a personal computer. The disk drive includes a magnetic disk rotatable around a spindle, arm (actuator arm) of a carriage turnable around a pivot, etc. A disk drive suspension is disposed on the distal end portion of the actuator arm.
The disk drive suspension includes a base plate fixed to the actuator arm, load beam attached to the base plate, flexure located along the load beam, etc. A slider is mounted on a tongue portion formed on the flexure. The slider is provided with an element (transducer) for reading or writing data.
As described in Jpn. Pat. Appln. KOKAI Publications Nos. 2007-287296 and 2008-004142, the base plate of the suspension is fixed to a suspension support portion of the actuator arm. For example, a boss portion formed on the base plate is inserted into a hole in the actuator arm. The boss portion is pressurized from inside by means of a jig. As the boss portion is plastically deformed (or increased in diameter), the base plate is fixed to the actuator arm.
When some suspensions were subjected to vibration tests, their sway vibration mode (resonance frequency across the slider) was found to be lower than a desired frequency. An intense investigation conducted by the inventors hereof revealed that this phenomenon is partly attributable to the state of a mounting area where the base plate is mounted on the actuator arm.
The suspension support portion (surface in contact with the base plate) of the actuator arm is precisely worked into a flat surface by grinding or the like. On the other hand, a mounting surface of the base plate that faces the suspension support portion is also worked into a flat surface by press working or the like. The base plate is formed by pressing a plate of a relatively soft metal, such as stainless steel. Thus, the surface accuracy after the press working is inevitably lower than that of the suspension support portion of the actuator arm.
In some cases, the base plate may be distorted or warped. If the base plate thus deformed is superposed on the suspension support portion of the actuator arm, the two may unstably contact each other, which was found to influence the vibrational characteristics of the suspension.